1. Field of the Invention
This invention relates to fluorescent lamp controllers and dimming controls for use therewith and more particularly to the provision of a dimming control which provides protective isolation between input terminals and lamp energizing circuitry and which facilitates accurate and safe control of light intensity over a wide range. The invention provides dimming controls which are efficient and highly reliable and are readily and economically manufacturable.
2. Background of the Prior Art
Prior art references relating to fluorescent lamp controllers are reviewed in the introductory portion of the specification of an application of Mark W. Fellows, John M. Wong and Edmond Toy, U.S. Ser. No. 219,923, filed July 15, 1988 now U.S. Pat. No. 4,952,849 issued Aug. 28, 1990, the disclosure of which is incorporated by reference. Such prior art references include the Wallace U.S. Pat. No. 3,611,021, the Stolz U.S. Pat. No. 4,251,752, the Stupp et al. U.S. Pat. Nos. 4,453,109, 4,498,031, 4,585,974, 4,698,554 and 4,700,113, and the Zeiler U.S. Pat. No. 4,717,863, relating to various forms of SMPS (Switch Mode Power Supply) circuits operative at high frequencies to obtain higher efficiency and other advantages in the energization of fluorescent lamps. The prior art also includes disclosures of circuits for control of the energization of fluorescent lamps to control intensity and effect dimming of the lamps when desired.